docs(plan): Day-7 implementation plan — drift, traceability, agents

docs(spec): Day-7 final-5% design — drift, traceability, agents

docs(plan): add Day-6 final-polish + demo-features plan

docs(plan): add Day-5 downstream-model + XAI + interactive plan

docs(plan): add Day-4 API/MLOps/frontend implementation plan

docs(plan): add Day-3 MRI ComBat pipeline plan

docs(plan): use correlation-based find_bads_eog to fix ICA on small recordings

docs: add Day 2 EEG MNE+ICA pipeline plan

chore: track planning docs and ignore .sixth/ tooling dir